The present invention relates to a cleaning device, particularly to a carpet sweeping device.
There are already known various devices of the type here under consideration. It is also already known to make the housing of such a device of synthetic plastic material, and particularly by assembling the housing from several parts. The carpet-sweeping devices are usually equipped with at least one cylindrical brush which is driven into rotation by an electric motor, the various movable or immovable components of the device being mounted on the housing or in recesses thereof. It is also already known to support the shaft of the rotor of the electric motor in plain or journal bearings which may be similarly accommodated in recesses provided in or on the housing.
The modern trend in designing and constructing such devices is to so configurate the housing that the various components of the device can be easily but reliably connected to the housing portions or shells during the assembly of the housing of the cleaning device so that an operative device is obtained after assembly of the housing shells.
In some types of such prior-art cleaning devices, the rotor of the electromotor is mounted in the synthetic plastic material housing of the cleaning device by means of conventional calotte journals which are mounted at the projecting end portions of the shaft of the rotor. It is further known to introduce such calotte journals into bearing recesses which are configurated as half-shells, such half-shells being constituted by portions of the housing, and to secure the bearings in such recesses by means of shells which abut against the projecting parts of the calotte bearings.
When the journals are so separately received in the housing, it is already known to cool such bearings or journals by means of cooling air which is blown or drawn through the electromotor, also cooling the same.
This solution to the cooling problem is possessed of several serious drawbacks. First of all, the journals which are supported in the synthetic plastic material housing in the above-mentioned half-shells, and which are acted upon a force acting in a predetermined direction resulting from the action of a driving belt on the shaft of the rotor, cannot be efficiently cooled by heat conduction. Thus, the respective journal bearing transmits a substantial part of the heat generated therein during the operation of the device to the synthetic plastic material of the housing. Under certain circumstances, especially after an extended period of use of the device, the synthetic plastic material of the housing may melt or become flowable so that the journal bearings may eventually move out of the bearing half-shell. It is further disadvantageous that the so-constructed journal bearings are not provided with a protective shielding which would cover the journal bearing from all sides so that, when the device is used for an extended period of time, the lubricant may flow out of the bearing and onto the surrounding portions of the housing or other components of the device. This is disadvantageous not only because of the fact that such lubricant soils the environment of the bearing, but primarily for the reason that the bearing is deprived of such escaped lubricant and it is very hard, if not impossible, to replenish the lubricant in the journal bearing.
A further disadvantage of the prior-art devices is that the housing of the device is provided with inlet and outlet openings for the cooling air which are usually not aligned with one another in the axial direction of the electric motor. As a result of this arrangement, the flow of the air through the interior of the housing must be diverted downstream of the electric motor to escape through the outlet opening, which may result in recirculation of a part of the already heated cooling air and, in either event, the cooling air which has already been heated by the passage thereof through the electric motor arrives at and dwells in the vicinity of the bearing which is located to the other axial side of the electric motor from the blower element which advances the air through the interior of the housing, so that the cooling effect of such already heated air on the above-mentioned bearing is, in most instances, completely insufficient.
A further drawback of the prior-art cleaning devices of the type here under consideration, that is such devices at least a housing of which can be damaged or destroyed by excessive heat, is that the sparks which are generated at the interface of a commutator and a respective commutator brush must be prevented from coming into contact with the material of the housing, for which purpose the prior art has proposed various rather complex and expensive measures.